Disk drives are widely used in computers, consumer electronics and data processing systems for storing information in digital form. The disk drive typically includes one or more storage disks and one or more head suspension assemblies. Each head suspension assembly includes a slider assembly which has an air bearing surface, a leading edge, a trailing edge and a read/write head positioned near the trailing edge. The read/write head transfers information to and from the storage disk. Rotation of the storage disk causes the slider assembly to ride on an air-supported journal bearing (also referred to as an “air bearing”) so that the read/write head is at a distance from the storage disk that is commonly referred to as a “head-to-disk spacing”.
Because today's disk drives utilize storage disks having increasingly high densities of data tracks, decreasing the head-to-disk spacing has become of great importance. However, this desire for a very small head-to-disk spacing must be balanced with tribological concerns in order to avoid damage to the read/write head and/or the storage disk, as well as loss of data.
Maintaining a relatively small and consistent head-to-disk spacing is further complicated by other factors. In particular, ambient pressure increases or decreases due to changes in altitude, for example, can cause the air bearing to ride at a higher or lower level relative to the storage disk, likewise causing a change in the head-to-disk spacing during various operations of the disk drive. More specifically, it is well known that with conventional disk drives, the head-to-disk spacing tends to decrease at higher altitudes. In fact, the head-to-disk spacing can decrease by approximately 10-30 percent, or roughly 1.5 nanometers at 10,000 feet above sea level. As a consequence, these changes in head-to-disk spacing can result in head-to-disk contact at relatively high altitudes, or an excessive head-to-disk spacing at relatively low altitudes. Either of these conditions can potentially cause one or more of the following adverse effects: off-track writing, degraded data transfer rates, damage to the slider assembly, damage to the storage disk, permanent data loss and/or other related problems.